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package com.oracle.svm.hosted.webimage.codegen.phase;

import com.oracle.svm.core.graal.phases.RemoveUnwindPhase;

import jdk.graal.compiler.nodes.StructuredGraph;
import jdk.graal.compiler.nodes.java.MonitorEnterNode;
import jdk.graal.compiler.nodes.java.MonitorExitNode;
import jdk.graal.compiler.nodes.spi.CoreProviders;
import jdk.graal.compiler.phases.BasePhase;

/**
 * This phase removes all {@link MonitorEnterNode} and {@link MonitorExitNode}.
 * <p>
 * This allows the {@link RemoveUnwindPhase} to remove more nodes. Without this, the exception edge
 * may contain a (useless) {@link MonitorExitNode} followed by a rethrow of the exception, which
 * prevents {@link RemoveUnwindPhase} from removing the exception edge.
 */
public class RemoveMonitorPhase extends BasePhase<CoreProviders> {
    @Override
    protected void run(StructuredGraph graph, CoreProviders context) {
        for (MonitorExitNode monitorExitNode : graph.getNodes(MonitorExitNode.TYPE)) {
            graph.removeFixed(monitorExitNode);
        }
        for (MonitorEnterNode monitorEnterNode : graph.getNodes(MonitorEnterNode.TYPE)) {
            graph.removeFixed(monitorEnterNode);
        }
    }
}
